Flux Spectrograms

Instrumental Page

Hill 2004 AIP
Krimigis et al. 2004 AIP
Krimigis et al. 2003 Nature
Hill et al. 2003 JGR
Hill et al. 2003 ICRC
Hill & Hamilton 2003 ICRC
Hill et al. 2002 ApJ
Hill et al. 2001 ICRC
Hill et al. 2001 JGR
Hamilton et al. 1999 ICRC
Hill 2001 PhD-Thesis
Hill 1998 MS-Thesis (pdf)
Hill 1998 MS-Thesis (html)
Hamilton et al. 1997 ICRC

LECP Researchers
Prof. Douglas C. Hamilton
Dr. Matthew E. Hill
Prof. George Gloeckler

1. ACR Oxygen Transport
2. ACR & SEP Spectrograms
3. 151-Day ACR Periodicity
4. Large ACR Oxygen Increase

Related Sites
Voyager Project Home Page
JHU/APL Voyager LECP Site
U. of Kansas LECP Site
Return to the UMD LECP Page

University of Maryland

Voyager LECP Home Page

The Low Energy Charged Particle (LECP) instruments aboard the Voyager 1 and 2 spacecraft make composition measurements of energetic particles above about 0.3 MeV/nucleon.  Using one or both of the LECP instruments, observations have been made of magnetospheric ions during each of the four Voyager planetary encounters (Jupiter, Saturn, Uranus and Neptune) since the 1977 launches.   Presently, and between the planetary encounters, the LECP experiment has returned unique interplanetary data regarding energetic ions in the heliosphere, (currently, Voyager 1 is the most remote human artifact, at a distance of 81 AU or about seven billion miles from the sun, nearly twice the distance of Pluto's orbit).  In the outer heliosphere, the LECP observations contribute to the understanding of the so called anomalous cosmic rays (ACRs) which dominated during the solar-minimum conditions typical of the mid, to late 1990's.  ACRs are thought to originate as ambient neutral atoms that enter the heliosphere due to the relative motion of our solar system through the local interstellar medium (LISM).  Then some of these neutrals become ionized, "picked-up" by the expanding solar wind, and accelerated at the solar wind termination shock (where the solar wind velocity drops from super- to sub-sonic).  Some of the population of accelerated "pick-up" ions at the termination shock, now called anomalous cosmic rays, diffuse and/or drift back in toward the inner heliosphere and are subject to modulation due to propagating solar disturbances.  It is at this stage, as the ACRs are transported from the remote heliosphere back toward the sun, that the LECP measurements are made.  Since ACRs are influenced by the broad phenomena listed above, the study of these heliospheric constituents may bear on the physics of the sun, heliosphere, termination shock, and local interstellar medium.

( Hits Since 14-AUG-2000)

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This page is maintained by M. E. Hill ( and was last updated on 26 February 2007.